Base for heat sink

ABSTRACT

A heat sink base ( 10 ) includes a rectangular body ( 11 ) made of aluminum and a circular core ( 12 ) made of copper. The body defines a circular through opening ( 111 ). A diameter of the opening is slightly less than a diameter of the core. The core is attached within the body according to the following steps: a) pressing the core into the through opening of the body; b) stamping the core to cause it to plastically deform in radial directions and thereby become firmly combined with the body; and c) removing any burring of the core flowing out from the opening such that surfaces of the core and the body are coplanarly smooth.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to bases for heat sinks, and particularly to bases consisting of two different metals for improving heat conductivity.

[0003] 2. Prior Art

[0004] Computer electronic devices such as central processing units (CPUs) frequently generate large amounts of heat, which can destabilize operation and cause damage. A heat sink placed in thermal contact with an electronic device mounted on a socket transfers heat from the electronic device through conduction.

[0005] A conventional heat sink comprises a base and a plurality of fins extending upwardly from the base. A central portion of the base is secured in contact with an electronic device, to conduct heat from the device to a top surface of the base. The heat is then conducted to the fins and dissipated by the fins. The base is often integrally made of aluminum or aluminum alloy. Aluminum and aluminum alloy have relatively low coefficients of heat conduction. Thus the heat generated by the device is not effectively transferred to the top surface of the base.

[0006] Improvements on such bases have been developed. FIGS. 4 and 5 show an improved base 2. The base 2 comprises a body 3 made of aluminum, and a plate 4 made of copper. The body 3 defines a recess 5 in a bottom surface thereof. The plate 4 is fixed within the recess 5 by means of welding with an intermediate layer of tin 6. The plate 4 contacts an electronic device to transfer heat from the device to the body 3. Unfortunately, the coefficient of heat conduction of tin (67 w/cm. k) is much lower than that of copper (359 w/cm. k) and that of aluminum (207 w/cm. k). Thus the layer of tin 6 between the plate 4 and the body 3 retards heat conduction between the plate 4 and the body 3, thereby reducing the efficiency of heat dissipation.

SUMMARY OF THE INVENTION

[0007] Accordingly, an object of the present invention is to provide a heat sink base having a highly heat-conductive core directly connected within the base to thereby facilitate heat conduction.

[0008] To achieve the above-mentioned object, a heat sink base in accordance with the present invention comprises a rectangular body made of aluminum and a circular core made of copper. The body defines a circular through opening in a central portion thereof. A diameter of the opening is slightly less than a diameter of the core. The core is attached within the body according to the following steps: a) pressing the core into the through opening of the body; b) stamping the core to cause it to plastically deform in radial directions and thereby become firmly combined with the body; and c) removing any burring of the core flowing out from the opening such that surfaces of the core and the body are coplanarly smooth.

[0009] Other objects, advantages and novel features of the present invention will be drawn from the following detailed embodiment of the present invention with attached drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is an exploded view of a heat sink base in accordance with the present invention;

[0011]FIG. 2 is an assembled view of FIG. 1;

[0012]FIG. 3 is a view of the base of FIG. 2 having a plurality of folded fins attached thereto;

[0013]FIG. 4 is an exploded view of a conventional base; and

[0014]FIG. 5 is an assembled view of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0015] Referring to the attached drawings, FIG. 1 is an exploded view of a base 10 constructed in accordance with the present invention. The base 10 comprises a rectangular body 11 and a circular core 12.

[0016] The body 11 is made of good heat conductive metallic material, such as aluminum. The body 11 comprises a top surface 112 and a bottom surface (not labeled) opposite to the top surface 112. A circular through opening 111 is defined in a central portion of the body 11.

[0017] The core 12 is made of material having heat conductivity higher than that of the body 11, such as copper. The core 12 comprises a bottom surface 121. A diameter of the core 12 is slightly larger than a diameter of the opening 111.

[0018] Referring also to FIG. 2, the core 12 is attached within the body 11 as follows: a) the core 12 is pressed into the opening 111 of the body 11; b) the core 12 is stamped to cause it to plastically deform outwardly in radial directions and thereby become firmly combined with the body 11; and c) any burring of the core 12 flowing out from the opening 111 is removed such that a top surface of the core 12 and the top surface 112 of the body 11 are coplanarly smooth, and the bottom surface 121 of the core 12 and a bottom surface of the body 11 are coplanarly smooth.

[0019] Referring also to FIG. 3, a plurality of folded fins 20 is then attached to the top surface 112 of the body 11 of the base 10 by conventional means.

[0020] In the present invention, the core 12 is in direct contact with the body 11 and the folded fins 20. An intermediate layer of connecting metal is not needed between the core 12 and the body 11. Relatively high heat resistance of a connecting metal such as tin is eliminated, thereby improving efficiency of heat conduction throughout the base 10. When the bottom surface 121 of the core 12 is in contact with an electronic device (not shown), heat generated by the electronic device is absorbed by the core 12 and then rapidly conducted to the body 11 and the fins 20. The heat is subsequently dissipated by the fins 20.

[0021] It is understood that the invention may be embodied in other forms without departing from the spirit thereof. Thus, the present example and embodiment is to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein. 

1. A method for forming a base of a heat sink on which heat dissipating fins are attached, the base comprising a body made of a first metal having a first heat conductivity and a core made of a second metal having a second heat conductivity higher than the first heat conductivity, the method comprising the following steps: a) defining an opening in the body which has a shape corresponding to a shape of the core and a size slightly less than a size of the core; b) pressing the core into the opening of the body; c) stamping the core to cause it to plastically deform in radial directions and thereby become firmly combined with the body.
 2. The method as claimed in claim 1, further comprising the following step after step c): d) removing any burring of the core flowing out from the opening such that surfaces of the core and the body are coplanarly smooth.
 3. The method as claimed in claim 2, wherein the opening is circular and the core is circular, and a diameter of the opening is slightly less than a diameter of the core. 4.The method as claimed in claim 3, wherein the opening is a through opening and is defined in a center of the body.
 5. The method as claimed in claim 1, wherein the body is made of aluminum and the core is made of copper.
 6. A method for forming a heat sink for dissipating heat generated by an electronic device, the method comprising the following steps: a) preparing a base, the preparing comprising the steps of: i) providing a body made of a first metal having a first heat conductivity, said body being formed with an opening therein; ii) providing a core made of a second metal having a second heat conductivity higher than the first heat conductivity, said core having a shape corresponding to a shape of the opening and a size slightly larger than a size of the opening, said core having a bottom face adapted for thermally contacting the electronic device; iii) pressing the core into the opening; and iv) stamping the core to cause it to plastically deform in radial directions, whereby the core and the body are securely connected together; and b) Preparing heat dissipating fins and attaching the fins to a top surface of the base.
 7. The method as claimed in claim 6, further comprising the following step after step iv): v) removing any burring of the core flowing out from the opening such that surfaces of the core and the body are coplanarly smooth.
 8. The method as claimed in claim 6, wherein the opening is circular and the core is circular, and a diameter of the opening is slightly less than a diameter of the core.
 9. The method as claimed in claim 8, wherein the opening is a through opening and is defined in a center of the body.
 10. The method as claimed in claim 6, wherein the body is made of aluminum and the core is made of copper. 